The large need of nitrogen (N) for crop production and the negative impacts of fertilizer on the environment result in a compelling need to identify new or advanced N management practices to reduce N losses while maintaining productivity and profitability. Nitrate (NO3) leaching, nitrous oxide (N2O) denitrification, and ammonia (NH3) volatilization are the most common pathways of N loss when synthetic N fertilizer is applied in agricultural lands. The objectives of this 7-year study (2014-2020) were to evaluate the use of traditional management practice (urea applied at pre-plant) and advanced N management practices [controlled-release fertilizer (ESN) and split applications with a urease inhibitor] on i) N losses (NO3, N2O, and NH3); ii) corn yield and profitability; and iii) cropping system N balance including plant N removal and soil N status. Integration of all the variables measured into a N balance calculation showed to be a poor approach to estimate N efficiency or impact on environmental quality because plant N uptake overshadow treatment influence on N loss measurements. Our findings indicate that pre-plant ESN can be considered a strategy to reduce N losses while maintaining crop yield. While split treatments increased corn yield, they did not reduce N losses, which contrasts the common assumption held by many that split applications are better for the environment. Nonetheless, the traditional management practice of pre-plant urea was the least efficient, producing lower crop yields and increasing N losses compared to pre-plant ESN in wet years. This demonstrates that there are N management practices that can improve production and environmental protection and their merit should be explored and refined further.
Sonia Thais Menegaz's master’s thesis defense
Tuesday, August 17, 2021 | 8 AM